F UNIT 2: RM 12 Lesson 3: Determining Subatomic Particles

UNIT 2: Matter and Energy
RM 12
Lesson 3: Determining Subatomic Particles
Determining Subatomic Particles
9
atomic number
F
element symbol
atomic mass
round to determine the
mass number
18.998
Fluorine
element name
Atomic Number = Number of Protons = Number of Electrons
A = P= E
Mass Number – Atomic Number = Number of Neutrons
M – A = N
Here is another way to determine protons, neutrons, and electrons using the
mnemonic APEMAN:
Fluorine (F)
Atomic number
9
Protons
9
Electrons
9
Mass number
19
–Atomic number
9
Neutrons
10
Gateways to Science, STAAR Edition, Grade 8
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